An imperial gallon is exactly 4.54609 liters.
Imperial gallons to Liters Converter — imp gal to L
Convert Imperial gallon (imp gal) to Liter (L) using the exact conversion factor (1 imperial gallon = 4.54609 liter). See the formula, worked examples, conversion table, unit comparison, history, and common uses.
Imperial gallons to Liters converter
Converter
Volume Converter
Convert metric, US customary, imperial, cooking, dry, and industrial volume units.
Context values
Some unit families need one extra value for a physically accurate result.
A liter is one cubic decimeter.
Result = input x 0.00454609 / 0.001.
Volume uses the cubic meter as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Imperial gallons to Liters
Imperial gallon and Liter appear side by side at fuel pumps and on beverage labels, since the US measures liquids in gallons while most of the world uses liters. Imperial gallon is typically associated with united Kingdom, Canada (some contexts), and other Commonwealth countries, while Liter is typically associated with standard volume unit for liquids worldwide, including in the US for beverages and fuel labeling in some contexts.
Formula
liters = imperial gallons × 4.54609
This factor comes from each unit's defined relationship to the category's base unit: 1 imperial gallon equals 0.00454609 base units, and 1 liter equals 0.001 base units, so dividing one by the other gives the direct imperial gallon-to-liter factor of 4.54609.
Simple example
1 imp gal × 4.54609 = 4.54609 L
1 imperial gallon = 4.54609 liters.
Real-world example
10 imp gal × 4.54609 = 45.4609 L
10 imperial gallons = 45.4609 liters.
Conversion table
| Imperial gallon (imp gal) | Liter (L) |
|---|---|
| 1 imp gal | 4.54609 L |
| 5 imp gal | 22.73045 L |
| 10 imp gal | 45.4609 L |
| 25 imp gal | 113.65225 L |
| 50 imp gal | 227.3045 L |
| 100 imp gal | 454.609 L |
Reverse conversion: Liter to Imperial gallon
4.54609 L × 0.2199692483 = 1 imp gal
4.54609 liters = 1 imperial gallons.
imperial gallons = liters × 0.219969248299
For a page dedicated to this direction, see Liter to Imperial gallon.
Imperial gallon vs. Liter
| Aspect | Imperial gallon | Liter |
|---|---|---|
| Family | UK/imperial customary unit | Non-SI metric unit accepted for use with SI |
| Typical use | UK fuel and beverage measurement (historically; UK now primarily uses liters for retail) | Beverage, fuel, and liquid product packaging worldwide |
| Where it's used | United Kingdom, Canada (some contexts), and other Commonwealth countries | Standard volume unit for liquids worldwide, including in the US for beverages and fuel labeling in some contexts |
Understanding the Imperial gallon
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
Where it's used: United Kingdom, Canada (some contexts), and other Commonwealth countries
Imperial gallon vs. US gallon. Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Uses of the Imperial gallon today
- UK fuel and beverage measurement (historically; UK now primarily uses liters for retail)
- Commonwealth country liquid measurement in some contexts
History of the Imperial gallon
The imperial gallon was created by Britain's Weights and Measures Act of 1824, defined as the volume of 10 pounds of water, replacing several inconsistent older English gallon definitions (wine gallon, ale gallon, corn gallon) with one standard.
Historical origin. Imperial gallon was not the invention of a single named person; it developed through the process described above.
Understanding the Liter
Liter (L) measures volume. A liter is defined as exactly one cubic decimeter (0.001 cubic meters). It is classified as a Non-SI metric unit accepted for use with SI.
Where it's used: Standard volume unit for liquids worldwide, including in the US for beverages and fuel labeling in some contexts
Uses of the Liter today
- Beverage, fuel, and liquid product packaging worldwide
- Cooking and recipe measurement in metric countries
- Laboratory and scientific volume measurement
History of the Liter
The liter was introduced with the French metric system in 1795, originally defined as the volume of one kilogram of pure water at its freezing point — tying volume, mass, and the meter together.
Between 1901 and 1964, the liter was briefly redefined as the volume of exactly one kilogram of water at its maximum density (about 4 °C), which made it very slightly larger than a cubic decimeter. It was redefined back to exactly one cubic decimeter in 1964, the definition still used today.
Historical origin. Liter was not the invention of a single named person; it developed through the process described above.
Imperial gallon — sources
- UK Weights and Measures Act 1824 — Establishes the imperial gallon definition.
Liter — sources
- BIPM SI Brochure — Non-SI units accepted for use with SI — Current cubic-decimeter definition of the liter.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many liters are in 1 imperial gallon?
1 imperial gallon equals 4.54609 liters, using the exact defined conversion factor rather than an estimate.
How do I convert imperial gallon to liter?
Multiply the imperial gallon value by 4.54609. The converter above does this instantly to whatever precision you set.
How do I convert liter back to imperial gallon?
Use the reverse factor: 1 liter equals 0.2199692483 imperial gallons. You can also use the swap control in the converter above to flip the direction instantly.
What is a imperial gallon?
Imperial gallon (imp gal) measures volume. The imperial gallon is defined as exactly 4.54609 liters, about 20% larger than the US gallon. It is classified as a UK/imperial customary unit.
What is a liter?
Liter (L) measures volume. A liter is defined as exactly one cubic decimeter (0.001 cubic meters). It is classified as a Non-SI metric unit accepted for use with SI.
Is the imperial gallon to liter conversion exact?
Yes. A liter is defined as exactly one cubic decimeter (0.001 cubic meters). That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between imperial gallon vs. us gallon?
Britain's 1824 Weights and Measures Act defined a new gallon based on 10 pounds of water, replacing the old wine gallon the US had already adopted — leaving the US (3.785 L) and imperial (4.546 L) gallons about 20% apart today.
Where is the imperial gallon still used today?
United Kingdom, Canada (some contexts), and other Commonwealth countries